On 2018/2/12 11:40, Jaegeuk Kim wrote:
> On 02/12, guoweichao wrote:
>>
>>
>> On 2018/2/12 10:32, Jaegeuk Kim wrote:
>>> On 02/12, guoweichao wrote:
>>>> Hi Jaegeuk,
>>>>
>>>> On 2018/2/12 7:32, Jaegeuk Kim wrote:
>>>>> On 02/06, Weichao Guo wrote:
>>>>>> There is a potential inconsistent metadata case due to a cp block
>>>>>> crc invalid in the latest checkpoint caused by hardware issues:
>>>>>> 1) write nodes into segment x;
>>>>>> 2) write checkpoint A;
>>>>>> 3) remove nodes in segment x;
>>>>>> 4) write checkpoint B;
>>>>>> 5) issue discard or write datas into segment x;
>>>>>> 6) sudden power-cut;
>>>>>> 7) use checkpoint A after reboot as checkpoint B is invalid
>>>>>>
>>>>>> This inconsistency may be found after several reboots long time later
>>>>>> and the kernel log about cp block crc invalid has disappeared. This
>>>>>> makes the root cause of the inconsistency is hard to locate. Let us
>>>>>> separate such other part issues from f2fs logical bugs in debug version.
>>>>>>
>>>>>> Signed-off-by: Weichao Guo <guoweic...@huawei.com>
>>>>>> ---
>>>>>> fs/f2fs/checkpoint.c | 8 ++++++--
>>>>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>>>>> index 8b0945b..16ba96a 100644
>>>>>> --- a/fs/f2fs/checkpoint.c
>>>>>> +++ b/fs/f2fs/checkpoint.c
>>>>>> @@ -737,13 +737,17 @@ static int get_checkpoint_version(struct
>>>>>> f2fs_sb_info *sbi, block_t cp_addr,
>>>>>> crc_offset = le32_to_cpu((*cp_block)->checksum_offset);
>>>>>> if (crc_offset > (blk_size - sizeof(__le32))) {
>>>>>> f2fs_msg(sbi->sb, KERN_WARNING,
>>>>>> - "invalid crc_offset: %zu", crc_offset);
>>>>>> + "invalid crc_offset: %zu at blk_addr: 0x%x",
>>>>>> + crc_offset, cp_addr);
>>>>>> + f2fs_bug_on(sbi, 1);
>>>>>
>>>>> I don't think we can use bug_on here, since we're easily getting this when
>>>>> power-cut happened in the middle of checkpoint pack writes, which is an
>>>>> expected
>>>>> behavior. Hmm, we need to consider another way to detect that.
>>>> We only check CP block crc here. The two CP blocks may have different CP
>>>> versions when
>>>> power-cut happened, but their crc value should be valid. IMO, this patch
>>>> will trigger a
>>>> bug_on only when some external issues cause CP block crc invalid as one 4K
>>>> page is
>>>> persisted atomically.
>>>
>>> Huh? This checks crc_offset, not crc? Unfortunately, my simple fault
>>> injection
>>> test gave this bug_on within a day. The below bug_on seems what you're
>>> saying
>>> about tho.
>> oh sorry, I didn't notice the code line carefully. But which fault injection
>> trigger
>> this bug_on? The crc_offset is also parts of the CP block, it seems
>> power-cut happened
>> in middle of writing checkpoint should not produce an invalid crc_offset.
>
> The second cp block can have stale data used by previous part of checkpoint.
Yes, but in all CP packs, a cp block crc_offset should always be CHECKSUM_OFFSET
which is configured at mkfs, right? I'm still not figure out why crc_offset
invalid
in the stale data of previous part of checkpoint?
Thanks,
>
>>
>> Thanks,
>>
>>>
>>>>
>>>> Thanks,
>>>>>
>>>>> Thanks,
>>>>>
>>>>>> return -EINVAL;
>>>>>> }
>>>>>>
>>>>>> crc = cur_cp_crc(*cp_block);
>>>>>> if (!f2fs_crc_valid(sbi, crc, *cp_block, crc_offset)) {
>>>>>> - f2fs_msg(sbi->sb, KERN_WARNING, "invalid crc value");
>>>>>> + f2fs_msg(sbi->sb, KERN_WARNING,
>>>>>> + "invalid crc value at blk_addr: 0x%x", cp_addr);
>>>>>> + f2fs_bug_on(sbi, 1);
>>>>>> return -EINVAL;
>>>>>> }
>>>>>>
>>>>>> --
>>>>>> 2.10.1
>>>>>
>>>>> .
>>>>>
>>>
>>> .
>>>
>
> .
>
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
